Fluid seal construction



P 1941- c. KURZWEIL FLUID SEAL CONSTRUCTION Filed Oct. 16, 1939 FIG.2.

INVENTOR. CHRIS KURZWEIL BY i AQ wvMw ATTORNEYS afentcrl Apr. 8, 1941 FLUID SEAL CONSTRUCTION Chris Kurgweil, Pontiac, Mich, assignor to Baldwin Rubber Company, Pontiac, Micln, a corporation of Michigan 'Application October 16, 1939, Serial No. 299,727

2 Claims.

This invention relates generally to seals and refers more particularly to improvements in seals of the type employed to prevent the escape of fluid along a cylindrical surface.

It is one of the principal objects of thisinvention to provide a relatively simple inexpensive seal which is highly effective to prevent the escape of fluid along a cylindrical surface of a member regardless of whether the latter is statiory, rotatable and/ or reciprocable.

l iother object of this invention resides in the provision of a seal of the type set forth wherein the area of the seal contacting the cylindrical surface is so small that the resulting friction is practically negligible. This feature is of particular importance when the seal is used in connection with a rotatable and/or reciprocable memher in that it reduces wear of the seal to a minirnu.

.htill another object of this invention which contributes materially to maintaining a fluidtlght seal around the cylindrical surface of the member with the minimum amount of wear of the seal resides in the provision of a seal in the form of a resilient bushing having the inner surface relieved intermediate the ends thereof in a manner to provide each end of the bore with an annular lip or edge continuously engageable with the cylindrical surface on-the member throughout the circumference of said surface. In accordance with this invention, each annular edge or lip has a substantially line contact with the cylindrical surface throughout the circumference thereof and both edges cooperate to prevent leakage in opposite directions along the cylindrical surface past the seal. In certain applications of the seal, one of the lips may be used to prevent the escape of fluid past the seal in one direction and the other lip may be employed to prevent the escape of dust or foreign matter past the seal in the other direction.

A further advantageous feature of the present invention resides in the provision of a seal of the above type so constructed that it will maintain an effective seal around the cylindrical surface even after the resilient material of the seal becomes set due to-ageing and, in addition, accomplishes this result without introducing excessive friction. In accordance with the present invention, the opposite ends of the seal are provided with a series of recesses spaced around the sealing lips. These recesses afford sufficient flexibility or working of the resilient material to permit substantial compression of the sealing lips without introducing excessive friction and without disturbing the continuous contact of the lips with the cylindrical surface In other words, the above construction renders it possible to provide a greater differentiation between the internal diameter of the lips and the external diameter of the cylindrical surface.

The foregoing, as well as other objects, will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawing, wherein:

Figure l. is anend elevational view of a, seal constructed in accordance with this invention;

Figure 2 is a cross sectional View taken substantially on the plane indicated by the line 22 of Figure l.

The reference character I0 designates a seal comprising a retainer ii and a block of resilient material i2 secured within the retainer ii. In the present instance, the retainer ii is in the form of a steel ring and the block it isin the form of a bushing fashioned of rubber or rubberlike material. The bushing is preferably vulcanized in the retaining ring ill and is adapted to receive a member it having a cylindrical surface it. For the purpose of illustration, the member i3 is shown in the drawing as being a shaft having a cylindrical surface and this shaft may be stationary, rotatable and/or reciprocable. Referring more particularly to Figure 2, it will be noted that the surface 15 of the bushing, surrounding the here, is relieved intermediate the ends of the bore to provide a substantial clearance i6 between the bushing and the cylindrical surface it on the member l3. In the present instance, the surface l5 of the bore has a constant radius of curvature from one end of the bore to the other and this radius is predetermined to provide annular edges in the form of lips ii on the bushing at opposite ends of the bore of less diameter than the diameter of the cylindrical surface I on the shaft I3.- As a result, the edges ill have a continuous substantially "line contact with the cylindrical surface M at points spaced axially of the shaft l3 and cooperate to form a double-acting seal. For example, one of the lips may be used to prevent the escape of fluid past the seal in one direction and the other lip may be employed to prevent the escape of foreign matter past the seal in the opposite direction.

It is one of the important features of the present invention to permit compressing the sealing lips ii to such an extent that the latter will maintain a continuous engagement with the cylindrical surface on the shaft l3 even after the rubber material becomes set due to ageing in use and to accomplish this result without introducing undue friction in the assembly. The above features are obtained in accordance with this invention by fashioning a plurality of depressions l8 in each end of the bushing around the sealing lips I1. The depressions l8 are shown in Figure 1 as being closely spaced and are preferably in the form of conical recesses. With the above construction in mind, attention is called to the fact that rubber material ages during use and takes a definite set. It follows, therefore, that unless the sealing edges H are initially placed under suiiicient compression to compensate for setting of the rubber material without destroying the frictional engagement of the edges with the cylindrical surface, the seal will become defective. The recesses or depressions l8 previously referred to render it possible to place the edges or lips under sufficient initial compression to maintain an effective seal, regardless of setting of the rubber material and permit obtaining this result without introducing excessive friction.

Thus, from the foregoing, it will be observed that I have provided a relatively simple and inexpensive seal which is highly effective over a long period of use. It will also be noted that my improved seal comprises a relatively few parts and may be inexpensively manufactured and assembled.

What I claim as my invention is:

1- A seal cooperating with a cylindrical surface on a member to prevent the escape of fluid along the surface past the seal, comprising a bushing of rubber material adapted to receive the member and having inwardly extending annular edge portions at opposite ends of the bore frlctionally engageable with the cylindrical surface throughout the circumference of the latter, and a plurality of conically-shaped recesses formed in each end of the bushing around said edge portions.

2. A seal cooperating with a cylindrical surface on a member to prevent the escape of fluid along the surface past the seal, comprising a bushing of rubber material adapted to receive the member, said having the surface surrounding the member curved outwardly in the direction of the axis of the bushing from one end of the bushing'to the other end of said bushing to provide the opposite ends of the bushing with axially spaced annular edges of less diameter than the cylindrical surface of the member and frictionally engageable with the cylindrical surface, and a plurality of conically shaped recesses in each end of the bushing and spaced from each other around the axis of the bushing for allowing the working ofthe rubber material required to permit the annular edges on the bushing to be placed under sufllcient initial compression to insure maintaining an effective seal around the cylindrical surface regardless of the set taken by the rubber material during use.

CHRIS KURZWEIL. 

